This invention relates to machines for polishing metals which comprise an abrasive band running about a pair of wheels. One wheel is generally driven by an electric motor and another is set at a height such that the operator may present the object to be polished to a part of the band.
Prior art polishing machines are not entirely satisfactory because the wheel on which the object is polished is obstructed at one of its sides by the drive motor and also by the protective housing surrounding the band and part of the wheel, thereby limiting the orientation of the object during the polishing operation. Furthermore, the object to be polished is presented to the curved part of the band, whose abrasive grains at that part are momentarily spaced apart. This local deformation is accentuated, because of the tensioning of the band and its speed, the grains closing up when the band becomes rectilinear again.
Another inconvenience inherent in these arrangements resides in the fact that the part of the band to which the object is presented is deformed not only in the longitudinal direction, but also in the transverse direction, and particularly when the object to be polished is put into contact with the lateral edges of the band. With this double deformation, the bands generally retain their strength only with difficulty. Furthermore, the momentary spacing of the grains of abrasive at the precise place where the object to be polished is presented tends during the course of the polishing to clog or fill up the band, which results in poor performance of the machine, and even to scratch the polished object if the band is not changed before the clogging of it becomes too great. Moreover, such machines are expensive in use.
The present invention remedies these inconveniences.
This remedy is achieved in a band-type polisher which permits operating the objects to be polished without their coming into contact with the structural parts of the machine during polishing, and which permits prolonged use of the band for better efficiency of the machines, this efficiency being in particular increased by the aid of means for giving the band the contours necessary for doing the polishing of objects in various local operations, each of these operations requiring only one pass on the band.
This remedy is further achieved according to the invention by providing a band-type polisher which comprises a drive wheel splined on the shaft of the drive motor, and which comprises a driven wheel mounted to rotate freely on a support connected to the structure of the polisher, this being characterized in that the said support forms a working head of a width substantially equal to that of the band, which working head is quite unobstructed on either side in order to not impair the orientation of the object being polished during the polishing operation.
Another novel characteristic of the polisher according to the present invention resides in the fact that it comprises a rotatable member mounted rotatably about an axle and so as to be able to turn in a plane going approximately through the longitudinal axis of the band and disposed so as to be able to turn between the pulleys and the lengths of the band between the pulleys, the rotatable member carrying at least one contact wheel mounted freely rotatably so that it can be driven momentarily by the belt, and provided with means to immobilize it so that the said contact wheel may be near the said driven wheel and also perpendicular of and substantially in the longitudinal axis of the band. The polisher further has means to apply the said contact wheel against the nonabrasive face of the band.
Another novel characteristic of the polisher according to the present invention resides in the polishing operation in which the object to be polished is placed into contact with the taut drive length of the band thus forming a plane surface.
The principal advantage of such a machine and of the process using the machine is that the polishing is done by putting the object to be polished into contact with the plane part of the band, whose abrasive grains are pressed closely together. Another advantage of the invention is inherent because of the fact that considering this arrangement, the band may be deformed without being deteriorated, this deformation being along its transverse direction.
The object to be polished is, therefore, put into contact with the band, this latter assuming the profile of the contact wheel against which it rests, so as to polish in one operation one part of the object. A set of a number of contact wheels having different profiles facilitates the operation and permits a considerable savings of time.
Other advantages and characteristics of the invention will be apparent from reading the following description of an exemplary example, and from the annexed drawings: